This invention relates in general to a digital photofinishing system and more particularly to a digital photofinishing and printing system for making color reflection prints from color transparency film images.
Several problem areas need to be addressed when making color negative paper prints from color images on transparent media, such as film images. The object of the process is to make a pleasing reflection print from the transparent film image. The first problem is that color transparency slide images cannot be printed directly onto color negative paper. First, a color negative film intermediate image must be prepared, followed by a printing step onto color negative paper. Another alternative is to print onto special color transparency paper. These alternatives are either multi-step processes requiring considerable time to complete, or are poor in image quality because of unwanted color absorptions in the multiple sets of image dyes. Furthermore, neither process can be fully automated without considerable effort. Even if the latter processes could be automated, no options exist to correct for an inappropriate tone scale reproduction for a particular scene, or for poor sharpness in the final image, that is, there is only one film or paper option for printing all slide materials. It would be desirable to have a digital photo-processing and printing system that enables correction algorithms for the problems mentioned above.
Methods and systems have been described that are devoted to producing pictorial images on various media and devices from scenes captured on photographic film, via scanning, to produce a digital image, image processing, and output rendering. One such system captures scenes on film, scans film to produce a digital image, digitally processes the image, and produces via a laser printer a print on AgX paper. Schreiber (U.S. Pat. No. 4,500,919) discloses an image reproduction system that scans an image captured on film, displays the image on a video monitor, enables image processing, and produces output as an inked hardcopy. U.S. Pat. No. 4,979,032, Alessi et al., describes an apparatus, including a film scanner, a video monitor, an image processor, and an output device, to produce an image on an output medium visually matched to the image displayed on the monitor. U.S. Pat. No. 5,267,030, Giorgianni et al., describes a method and means to transform images captured on film, via digitization on a film scanner, to a color metric or other space, with an output onto a variety of media and devices. Buhr et al (U.S. Pat. No. 5,300,381) describes a pictorial imaging system that includes image capture on photographic film, film scanning to produce a digital image, image processing, and digital output. U.S. Pat. No. 5,579,132, Takahashi, describes an image processing system devoted to storing or producing images that have xe2x80x9csubstantially the same colorxe2x80x9d or additional xe2x80x9caesthetic color correctionxe2x80x9d versus the original scene, based on a variety of image processing transformations of the digitized image. U.S. Pat. No. 5,608,542, Krahe et al., describes a system that produces index prints based on scanning a film frame, image processing, and rendering. Giorgianni et al., in Digital Color Management Encoding Solutions, describes the process for converting from colorimetric tristimulus values for transparency viewing to similar values for reflection media viewing. A printer calibration process is described in U.S. Pat. No. 5,053,866, S. Johnson et al.
All of these articles or patents describe, in one form or another, processes for obtaining more pleasing prints from a film image capture other than from the conventional optical process.
According to the present invention, there is provided a solution to known reflection media rendering problems inherent to conventional optical or hybrid printing of transparent image media.
According to a feature of the present invention, there is provided a method of digital print preparation comprising the steps of: producing a digital color image having colorimetric tristimulus values describing a color transparency media from a color image captured on color transparency photographic media; first transforming the digital color image having colorimetric tristimulus values describing color transparency media to a digital color image having colorimetric tristimulus values describing a reflection print; second transforming the digital color image having colorimetric tristimulus values describing a reflection print into digital code values representative of the color image for printing by a digital color printer using a combination of 1D and 3D look up tables; sharpening the transformed digital code values representative of the color image with a sharpening algorithm optimized to avoid unacceptable artifacts; and digitally printing the sharpened digital color image onto reflection media.
The invention has the following advantages.
1. A pleasing reflection print is made from a color transparency film image.
2. Inappropriate reproduced tone scale and poor sharpness can be corrected for in a digital photofinishing operation.